Description: The deglaciation that followed the last ice age period was abruptly
and dramatically interrupted ~12,900 years ago by widespread cooling that marks
the onset of the Younger Dryas Cool Episode, an apparent climatic anomaly in
Quaternary deglaciation behavior. Much evidence shows that the Younger Dryas
onset was marked by abrupt changes in ice sheet configuration, diversion of
North American flood-waters to the northern Atlantic, the sudden emptying of
proglacial lakes, and the reorganization of thermohaline circulation that may
have triggered severe cooling. Nevertheless, significant questions have recently
emerged about timing and direction of major freshwater flows to the oceans, in
turn raising questions about the triggering mechanism for the Younger Dryas. The
onset of the Younger Dryas also appears to have coincided with massive,
widespread and punctuated changes in animal biota and Paleolithic cultural
development centered in North and South America. This is represented by the
well-known extinction of the megafauna of the Americas, including mammoths,
horses and groundsloths (the most recent of all mass extinctions) and the
termination of Clovis and certain other contemporaneous Paleolithic human
cultures. The cause of these changes is also highly controversial and much
debated, but is likely tied to the severe environmental changes that occurred at
the beginning of the Younger Dryas. Nevertheless, some researchers consider
these to be coincidental events, while others link the two as cause and effect.
Another hypothesis attributes the extinctions to overhunting by Clovis people
and other Paleolithic hunters or to pandemics associated with human migrations.
However, all these hypotheses appear to fall short in satisfactorily explaining
much available evidence. A new hypothesis posits that Younger Dryas cooling was
instead triggered by extraterrestrial impacts that caused ice sheet
destabilization, flood-water rediversion and changes in ocean circulation. This
work offers newly uncovered evidence for ET impact at 12.9 ka including
end-Clovis age sediments throughout North America with high levels of Iridium,
magnetic and carbon, spherules, glass-like carbon, fullerenes, and ET noble gas
ratios often in association with carbonaceous black layers and succeeded by
black mats with unusual biota In this session, we invite abstracts that will
explore the strengths and weaknesses of existing and new hypotheses that attempt
to explain the cause of the Younger Dryas and of associated changes in the
global environmental system, the associated extinctions, and of human cultural
changes. We welcome all abstracts exploring new perspectives on the chronology,
stratigraphic succession and potential interconnections between a wide-range of
processes that appear to have been associated with the Younger Dryas Episode.
These include abrupt climatic change, ice-sheet deglaciation, flood-water
rerouting, surficial geology, iceberg discharge, ocean reorganization including
thermohaline circulation, and sea-level change. Also critical is the timing and
nature of major extinction, Paleolithic cultural succession and impact-related
phenomena.

"Our research indicates that the entire Great Lakes
region (and beyond) was subjected to particle bombardment and a catastrophic
nuclear irradiation that produced secondary thermal neutrons from
cosmic ray interactions. The neutrons produced unusually large quantities of
239Pu and substantially altered the natural uranium
abundance ratios (235U/238U)
in artifacts and in other exposed materials including cherts, sediments, and the
entire landscape. These neutrons necessarily transmuted residual nitrogen (14N)
in the dated charcoals to radiocarbon, thus explaining anomalous dates."

-- From "Terrestrial Evidence of a Nuclear Catastrophe in Paleoindian Times"

A distant
supernova that exploded 41,000 years ago may have led to
the extinction of the mammoth, according to research
that will be presented tomorrow (Sept. 24) by nuclear
scientist Richard Firestone of the U.S. Department of
Energy’s Lawrence Berkeley National Laboratory.

Firestone, who conducted this research with Arizona
geologist Allen West, will unveil this theory at the 2nd
International Conference "The World of Elephants" in Hot
Springs, SD. Their theory joins the list of possible
culprits responsible for the demise of mammoths, which
last roamed North America roughly 13,000 years ago.
Scientists have long eyed climate change, disease, or
intensive hunting by humans as likely suspects.

Now, a supernova may join the lineup. Firestone and West
believe that debris from a supernova explosion coalesced
into low-density, comet-like objects that wreaked havoc
on the solar system long ago. One such comet may have
hit North America 13,000 years ago, unleashing a
cataclysmic event that killed off the vast majority of
mammoths and many other large North American mammals.
They found evidence of this impact layer at several
archaeological sites throughout North America where
Clovis hunting artifacts and human-butchered mammoths
have been unearthed. It has long been established that
human activity ceased at these sites about 13,000 years
ago, which is roughly the same time that mammoths
disappeared.

They also found evidence of the supernova explosion’s
initial shockwave: 34,000-year-old mammoth tusks that
are peppered with tiny impact craters apparently
produced by iron-rich grains traveling at an estimated
10,000 kilometers per second. These grains may have been
emitted from a supernova that exploded roughly 7,000
years earlier and about 250 light years from Earth.

“Our research indicates that a 10-kilometer-wide comet,
which may have been composed from the remnants of a
supernova explosion, could have hit North America 13,000
years ago,” says Firestone. “This event was preceded by
an intense blast of iron-rich grains that impacted the
planet roughly 34,000 years ago.”

In support of the comet impact, Firestone and West found
magnetic metal spherules in the sediment of nine
13,000-year-old Clovis sites in Michigan, Canada,
Arizona, New Mexico and the Carolinas. Low-density
carbon spherules, charcoal, and excess radioactivity
were also found at these sites.

“Armed with only a magnet and a Geiger counter, we found
the magnetic particles in the well-dated Clovis layer
all over North America where no one had looked before,”
says Firestone.

Analysis of the magnetic particles by Prompt Gamma
Activation Analysis at the Budapest Reactor and by
Neutron Activation Analysis at Canada’s Becquerel
Laboratories revealed that they are rich in titanium,
iron, manganese, vanadium, rare earth elements, thorium,
and uranium. This composition is very similar to lunar
igneous rocks, called KREEP, which were discovered on
the moon by the Apollo astronauts, and have also been
found in lunar meteorites that fell to Earth in the
Middle East an estimated 10,000 years ago.

“This suggests that the Earth, moon, and the entire
solar system were bombarded by similar materials, which
we believe were the remnants of the supernova explosion
41,000 years ago,” says Firestone.

In addition, Berkeley Lab’s Al Smith used the Lab’s
Low-Background Counting Facility to detect the
radioactive isotope potassium-40 in several Clovis
arrowhead fragments. Researchers at Becquerel
Laboratories also found that some Clovis layer sediment
samples are significantly enriched with this isotope.

“The potassium-40 in the Clovis layer is much more
abundant than potassium-40 in the solar system. This
isotope is formed in considerable excess in an exploding
supernova, and has mostly decayed since the Earth was
formed,” says Firestone. “We therefore believe that
whatever hit the Earth 13,000 years ago originated from
a recently exploded supernova.”

Image: Radiocarbon peaks in Icelandic marine sediment
samples, indicated by the black line, coincide with
three supernova-caused events that Firestone and Wells
believe led to the extinction of the mammoth

Firestone and West also uncovered evidence of an even
earlier event that blasted parts of the Earth with
iron-rich grains. Three mammoth tusks found in Alaska
and Siberia, which were carbon-dated to be about 34,000
years old, are pitted with slightly radioactive,
iron-rich impact sites caused by high-velocity grains.
Because tusks are composed of dentine, which is a very
hard material, these craters aren’t easily formed. In
fact, tests with shotgun pellets traveling 1,000
kilometers per hour produced no penetration in the
tusks. Much higher energies are needed: x-ray analysis
determined that the impact depths are consistent with
grains traveling at speeds approaching 10,000 kilometers
per second.

“This speed is the known rate of expansion of young
supernova remnants,” says Firestone.

The supernova’s one-two punch to the Earth is further
corroborated by radiocarbon measurements. The timeline
of physical evidence discovered at Clovis sites and in
the mammoth tusks mirrors radiocarbon peaks found in
Icelandic marine sediment samples that are 41,000,
34,000, and 13,000 years old. Firestone contends that
these peaks, which represent radiocarbon spikes that are
150 percent, 175 percent, and 40 percent above modern
levels, respectively, can only be caused by a cosmic
ray-producing event such as a supernova.

“The 150 percent increase of radiocarbon found in
41,000-year-old marine sediment is consistent with a
supernova exploding 250 light years away, when compared
to observations of a radiocarbon increase in tree rings
from the time of the nearby historical supernova SN
1006,” says Firestone.

Firestone adds that it would take 7,000 years for the
supernova’s iron-rich grains to travel 250 light years
to the Earth, which corresponds to the time of the next
marine sediment radiocarbon spike and the dating of the
34,000-year-old mammoth tusks. The most recent sediment
spike corresponds with the end of the Clovis era and the
comet-like bombardment.